Heretofore, field pick-up units (FPUs) have been known as an apparatus used in a radio communication system performing video transmission such as live broadcasting or emergency broadcasting of television. This FPU is used for material transmission in the broadcasting sector and performs radio communication using some of a frequency band shared with another system such as a transceiver. For this reason, it is necessary to always monitor the presence or absence of interference in the frequency band in use and to prevent interference with another system in FPUs. An FPU base station measures a reception level (interference amount), and when the reception level exceeds a predetermined threshold, the base station determines that another system has started using the frequency band (interference has occurred) and stops using the frequency band.
Meanwhile, a communication system has been known in which a turbo coding scheme and an orthogonal frequency division multiplexing (OFDM) communication scheme are combined and a multicarrier transmission apparatus maps systematic bits and parity bits to different subcarriers (see Patent Literature (hereinafter, referred to as “PTL”) 1).